^3 


PAPER  JN^O.  DL. 

A  COAL  CALORIMETER. 
By  Geo.  H.  Baurus. 

presented  at 

THE  MECHAOTCAL  EISTGINEERIKG  SECTIOJN" 

-B- 


OF  THE 


WORLD'S  ENGINEERING  CONGRESS,  CHICAGO,  ILL.,  U.  S.  A. 


JULY, 


Accepted  by  the  Council  of  the  American  Society  of  Mechanical  Engineers, 
and  to  form  part  of  Volume  XIV.  of  the  Transactions. 


For  additional  copies,  address — 

No.  12  West  31st  Street, 

New  York  City,  N.  Y.,  U.  S.  A. 


DL.* 

A  COAL  CALORIMETER. 

BY  GEO.  H.  BARRUS. 

In  view  of  the  prominence  given  to  the  determination  of  the 
quality  of  coal  used  on  locomotive  tests  by  the  employment  of  some 
form  of  oxygen  calorimeter,  which  is  given  in  the  report  of  the 
Committee  on  Locomotive  Tests  presented  at  this  meeting,  it  seems 
desirable  to  record  some  of  the  results  which  have  been  obtained 
by  the  use  of  one  form  of  the  instrument  referred  to,  as  designed 
and  operated  by  the  writer. 

The  instrument  has  been  employed  .for  the  past  three  years,  and 
during  that  time  samples  of  nearly  one  hundred  different  coals 
have  been  subjected  to  the  calorimeter  test.  iTo  definite  line  of 
investigation  has  been  undertaken  to  determine  the  heat  of  com- 
bustion of  selected  varieties  of  coal.  The  tests  have  been  made  on 
coal  which  has  been  used  on  evaporative  trials  of  boilers  which 
the  writer  has  conducted,  and  on  samples  which  have  been  sub- 
mitted to  him  from  time  to  time  by  clients  who  wished  the  value 
of  the  coal  obtained.  A  large  share  of  the  fuels  are  coals  mined  in 
Maryland,  Yirginia,  and  Eastern  Pennsylvania.  Few  coals  from 
points  in  the  United  States  farther  west  have  been  tried. 

It  is  proposed  here  to  give  a  brief  description  of  the  apparatus 
and  a  tabular  summary  of  the  results  of  a  portion  of  the  tests. 

The  complete  apparatus  is  shown  in  the  accompanying  half-tone 
cut.  The  calorimeter  itself,  which  lies  afc  the  right  near  the  tank, 
consists  of  a  glass  vessel  5  inches  in  diameter,  9^  inches  high, 
which  holds  the  water  of  the  calorimeter.  Submerged  in  the  inte- 
rior is  a  bell-shaped  glass  vessel  2\  inches  in  diameter,  4  inches  high, 
having  a  long  neck  |  inch  in  diameter,  which  is  closed  at  the  top 
with  a  stopper.  The  upper  end  of  the  neck  stands  5  inches  above 
the  top  of  the  outside  vessel.  The  glass  bell,  or  "combustion 
chamber,"  as  it  may  be  termed,  rests  upon  a  metal  base,  to  which 
it  is  held  by  means  of  spring  clips,  the  bottom  of  the  chamber 


*  Presented  at  the  Cbicago  meeting  (July,  1893)  of  the  American  Society  of 
Mechanical  Engineers,  and  forming  part  of  Volume  XIV.  of  the  Transactions. 


4 


A  COAL  CALOKIMETER. 


being  provided  with  an  exterior  rib  by  means  of  which  the  clips 
are  made  fast.  The  base  is  perforated,  and  at  the  centre  is  mounted 
a  short  tube,  for  the  reception  of  a  crucible,  in  which  the  combus- 
tion takes  place.  The  crucible  is  made  of  platinum.  It  is  sur- 
rounded by  a  layer  of  non-conducting  material,  which  is  placed 
between  it  and  the  outer  metal.  A  small  glass  tube  is  inserted  in 
the  stopper  at  the  top  of  the  neck,  and  this  is  carried  down  to  the 
interior  of  the  combustion  chamber.  It  is  fitted  somewhat  loosely, 
so  that  a  slight  pressure  will  move  it  up  or  down,  and  thereby 
adjust  its  lower  end  to  any  height  desired  above  the  crucible.  The 
tube  has  a  slight  lateral  movement  also,  so  that  it  may  be  directed, 
at  the  will  of  the  operator,  toward  any  part  of  the  crucible.  This 
tube  is  connected  with  a  tank  containing  oxygen  gas,  and  through 
it  a  current  of  gas  is  passed,  so  as  to  enable  the  combustion  of  the 
coal  to  be  carried  on  under  water.  The  pressure  of  the  gas  drives 
out  the  water  which  would  otherwise  fill  the  chamber,  and  keeps 
its  level  below  the  base.  The  products  of  combustion  rising  from 
the  crucible  pass  downward  through  the  perforations  in  the  base, 
escaping  around  the  edge  of  the  base,  and  finally  bubbling  up 
through  the  water,  and  emerging  at  its  surface.  A  wire  screen  is 
secured  to  the  neck  of  the  combustion  chamber,  extending  to  the 
sides  of  the  outer  vessel,  thereby  holding  back  the  gas  and  pre- 
venting its  immediate  escape  to  the  surface  of  the  water. 

In  making  a  test,  the  quantity  of  water  used  is  2  kilogrammes  or 
2,000  grammes,  and  the  quantity  of  coal  1  gramme.  The  equiva- 
lent calorific  value  of  the  material  of  the  instrument  is  185  milli- 
grammes. One  degree  rise  of  temperature  of  the  water  corresponds 
therefore  to  a  total  heat  of  combustion  of  2,185  B.  T.  U.  The 
number  of  degrees  rise  of  temperature  for  ordinary  coals  varies 
from  5|-°  to  6|-°  Fahr.  The  thermometer  used  for  determining  the 
temperature  of  the  water  is  graduated  to  twentieths  of  a  degree ; 
and  as  the  divisions  are  about  one-thirtieth  of  an  inch  apart,  they 
may  be  subdivided  by  the  eye  so  as  to  readily  obtain  a  reading  to 
hundredths  of  a  degree. 

The  scales  shown  at  the  extreme  left  of  the  cut  are  used  for 
weighing  out  the  water,  and  the  chemical  scales  shown  in  the  centre 
are  employed  in  weighing  the  coal  and  the  ash.  The  latter  are  sen- 
sitive to  a  fraction  of  a  milligramme. 

The  process  of  making  a  test  is  as  follows :  Having  dried  and 
pulverized  the  coal,  and  weighed  out  the  desired  quantities  of  coal 
and  water,  the  combustion  chamber  is  immersed  in  the  water  for  a 


A  COAL  CALOKIMETEK. 


5 


short  time,  so  as  to  make  the  temperature  of  the  whole  instrument 
uniform  with  that  of  the  water.  On  its  removal,  the  initial  tem- 
perature of  the  water  is  observed,  the  top  of  the  chamber  lifted,  the 
gas  turned  on,  and  the  coal  quickly  lighted,  a  small  paper  fuse 
having  previously  been  inserted  in  the  crucible  for  this  purpose. 
The  top  of  the  combustion  chamber  is  quickly  replaced,  and  the 
whole  returned  to  its  submerged  position  in  the  water.  The  com- 
bustion is  carefully  watched  as  the  process  goes  on,  and  the  current 
of  oxygen  is  directed  in  such  a  way  as  to  secure  the  desired  rate 
and  conditions  for  satisfactory  combustion.  When  the  coal  is  en- 
tirely consumed,  the  interior  chamber  is  moved  up  and  down  in 
the  water  until  the  temperature  of  the  whole  has  become  uniform, 
and  finally  it  is  withdrawn  and  the  crucible  removed.  The  final 
temperature  of  the  water  is  then  observed,  and  the  weight  of  the 
resulting  ash. 

The  initial  temperature  of  the  water  is  so  fixed  by  suitably  mix- 
ing warm  and  cold  water  that  it  stands  at  the  same  number  of  de- 
grees below  the  temperature  of  the  surrounding  atmosphere  (or 
approximately  the  same)  as  it  is  raised  at  the  end  of  the  process 
above  the  temperature  of  the  air.  In  this  way  the  effect  of  radi- 
ation from  the  apparatus  is  overcome,  so  that  no  provision  in  the 
matter  of  insulation  is  required,  and  no  allowance  needs  to  be 
made  for  its  effect. 

The  accompanying  table  presents  a  list  of  sixty-one  of  the  tests 
which  have  been  made  with  the  instrument.  In  many  cases  the 
name  of  the  mine  is  given,  but  in  a  large  number  the  only  informa- 
tion presented  regarding  the  locality  from  which  the  coal  was  ob- 
tained is  the  commercial  name  by  which  it  is  known  in  the  market. 
In  some  cases  merely  the  general  class  of  the  coal  is  stated,  whether 
bituminous  or  anthracite. 


3 


A  COAL  CALOKIMETER. 
RESULTS  OF  TESTS  WITH  THE  BARRUS  COAL  CALORIMETER. 

CUMBERLA^D  COAl.S. 


Kind  of  Coal :  Mine  or  Locality. 


George's  Creek  

"  (American  Co)  

"    (Md.  Coal  Co.)  

(G.  C.  Coal  and  Iron  Co.) 

George's  Creek  

Eureka  

George's  Creek  


S  o 
Ph 


7.6 

8.2 

6.1 

6.6 

8.6 

6.5 

7. 

5. 

5.1 

5.7 

6.1 

5.1 

7.5 

5.1 

5.4 

8. 

4.4 


Miscellaneous  Bituminous  Coals. 


Pocahontas 


Clearfield. 


New  River 


Welsh  (English)  

Lancashire  (English) . 


Sonman 


Elenora, 


Eclipse. 


6.2 

13,608 

4. 

14,121 

5. 

14,114 

6.5 

13,697 

3.2 

14,603 

4.7 

13,640 

11.1 

12,517 

0.6 

14,273 

1. 

14,455 

5.7 

13,858 

3.5 

13,922 

5. 

13,858 

4.1 

13,922 

7.7 

13,581 

6.8 

12,122 

8.7 

13,402 

11. 

12,983 

6.9 

18,326 

8.3 

13,267 

7. 

13,210 

7.5 

12,765 

6.8 

12.877 

7.6 

13,016 

9.1 

12,956 

2.7 

14.114 

5.2 

13,474 

A  COAL  CALORIMETER. 


7 


44 
45 
46 
47 
48 
49 
50 


Kind  of  Coal :  Mine  or  Locality. 


Elk  Garden  

Mixture  New  River  and  Cumberland 

Frontenac  (Kansas)   ... 

Cape  Breton  (Caledonia)  

Youghiogheny — lump  (Acme)  

"  — slack  (Pacific)  


16.5 
7.8 
6.7 

17.7 
8.7 
5.9 

10.2 


11,677 
13,180 
13,861 
10,506 
12.420 
12.941 
11,664 


Anthracite  Coals. 


51 
52 
53 
54 
55 
56 
57 
58 
59 
60 
61 


Honey  Brook — Chestnut  No.  2, 
Cross  Creek —        "  . 

Lackawana — Egg.  

Broken  


12. 

11,733 

.  10.5 

11,521 

17.5 

11.104 

9.1 

13,189 

,  10.6 

12,812 

14.5 

11,470 

,  11.7 

12,146 

10.9 

11,634 

,  9.3 

12,201 

15. 

11,086 

13.2 

12,412 

